Preeclampsia: a hyperdynamic disease model

Incidence of Interstitial Alveolar Syndrome on Point-of-Care Lung Ultrasonography in Pre-eclamptic Women With Severe Features: A Prospective Observational Study

BACKGROUND

Lung interstitial edema is a clinically silent pathology that develops before overt pulmonary edema among pre-eclamptic women with severe features. Point-of-care lung ultrasonography (LUS) has been suggested as an accessible bedside tool that may identify lung interstitial edema before developing clinical signs and symptoms. Thus, we planned to use bedside LUS as a diagnostic tool in admitted pre-eclamptic women with severe features, with the aim of identifying alveolar-interstitial fluid, seen as B-lines. Our primary objective was to assess the incidence of interstitial alveolar syndrome on lung ultrasonography.

METHODS

We conducted a prospective, single-center, observational study on parturients with pre-eclampsia with severe features over a period of 15 months. LUS in 4 intercostal spaces (ICS) was performed on all eligible patients. The number of single or confluent B-lines in each space was recorded by an independent observer. A scoring system was used to grade the lung fluid content based on the number of single and confluent B-lines per ICS, with scores ranging from 0 to 32 (low, 0-10; moderate, 11-20; and high, 21+). The incidence of B-lines at admission and before and after delivery was calculated. In addition, bedside 2D echocardiography was performed to assess left ventricular systolic and diastolic function. Any correlation between presence of B-lines on LUS and blood pressure, clinical symptoms, or echocardiography findings was assessed.

RESULTS

Seventy patients were enrolled in the study. On LUS, B-lines were seen in 64.3% patients at admission (45/70 vs 25/70 without B-lines; P = .02), 65.7% patients before delivery (46/70 vs 24/70 without B-lines; P = .01), and 58.6% patients 24 hours postpartum (41/70 versus 29/70 without B-lines; P = .15). Nearly all patients (94.3%) exhibited low to moderate severity of pulmonary fluid burden at admission. Echocardiography revealed diastolic dysfunction in 47.1% (n = 33/70) patients with associated B-lines in the majority (n = 32/33). The total B-line score and E/e' ratio among patients with diastolic dysfunction was found to be strongly correlated (r = 0.848; P < .001). All pre-eclamptic women with presence of breathlessness (11/11; 100%) and facial puffiness (16/16; 100%) on admission had B-lines on LUS.

CONCLUSIONS

We conclude that ultrasonographic pulmonary interstitial syndrome is present in more than half of the women with pre-eclampsia with severe features and correlates with diastolic dysfunction, high blood pressure records, and acute-onset breathlessness.

Preeclampsia has two phenotypes which require different treatment strategies

The opinion on the mechanisms underlying the pathogenesis of preeclampsia still divides scientists and clinicians. This common complication of pregnancy has long been viewed as a disorder linked primarily to placental dysfunction, which is caused by abnormal trophoblast invasion, however, evidence from the previous two decades has triggered and supported a major shift in viewing preeclampsia as a condition that is caused by inherent maternal cardiovascular dysfunction, perhaps entirely independent of the placenta. In fact, abnormalities in the arterial and cardiac functions are evident from the early subclinical stages of preeclampsia and even before conception. Moving away from simply observing the peripheral blood pressure changes, studies on the central hemodynamics reveal two different mechanisms of cardiovascular dysfunction thought to be reflective of the early-onset and late-onset phenotypes of preeclampsia. More recent evidence identified that the underlying cardiovascular dysfunction in these phenotypes can be categorized according to the presence of coexisting fetal growth restriction instead of according to the gestational period at onset, the former being far more common at early gestational ages. The purpose of this review is to summarize the hemodynamic research observations for the two phenotypes of preeclampsia. We delineate the physiological hemodynamic changes that occur in normal pregnancy and those that are observed with the pathologic processes associated with preeclampsia. From this, we propose how the two phenotypes of preeclampsia could be managed to mitigate or redress the hemodynamic dysfunction, and we consider the implications for future research based on the current evidence. Maternal hemodynamic modifications throughout pregnancy can be recorded with simple-to-use, noninvasive devices in obstetrical settings, which require only basic training. This review includes a brief overview of the methodologies and techniques used to study hemodynamics and arterial function, specifically the noninvasive techniques that have been utilized in preeclampsia research.

Performance of ophthalmic artery Doppler velocimetry in the complementary diagnosis of preeclampsia

OBJECTIVES

To calculate the accuracy (A) and establish the best cutoff value for ophthalmic artery (OA) Doppler velocimetry indexes in patients diagnosed with preeclampsia (PE), compared with healthy pregnant women.

METHODS

This prospective experimental study enrolled 268 women: 133 with PE and 135 healthy pregnant women. All patients were evaluated by OA Doppler sonography, bilaterally, to assess their pulsatility index (PI), resistance index (RI), peak systolic velocity (PVS), second peak systolic velocity (P2), end-diastolic velocity (EDV), and peak ratio (PR). Means were compared using Student's T-test. Receiver Operating Characteristics (ROC) curve was used to establish the cutoff value and estimate the sensitivity (S), specificity (Sp), accuracy (A) of all variables, and a significance of 95% was adopted.

RESULTS

ROC curve analysis showed that P2 and PR were superior to the other parameters for PE diagnosis. We tested two cutoff values: (1) using PR ≥0.70, obtained A: 88.72%, S: 81.95%, and Sp: 95.48% and (2) using PR ≥0.75, and A: 86.24%, S: 74.43%, and Sp: 99.24%. By adopting P2 ≥ 21.5 cm/s, we obtained A: 87.59%, S: 84.96%, and Sp: 90.22% and when the cutoff point was P2 ≥ 22 cm/s, there was a slight decrease in A to 86.46% and S to 81.20%, with Sp: 91.89.3%.

CONCLUSION

Ophthalmic artery Doppler demonstrated to be an effective and high-performance imaging method for the diagnosis of PE and the indexes P2 and PR demonstrated superior accuracy to the other Doppler parameters assessed. Higher performance occurred when the cutoff values with greater specificity were adopted, PR ≥ 0.75 and P2 ≥ 22 cm/s, considering that the proposed OA Doppler is to be a complementary method for preeclampsia.

Relationship between ophthalmic artery Doppler and maternal cardiovascular function

OBJECTIVE

In mid-gestation, the finding of an increase in the ophthalmic artery second to first peak of systolic velocity ratio (PSV ratio) provides useful prediction of subsequent development of pre-eclampsia (PE). The objective of this study of an unselected population at 19-23 weeks' gestation was to gain a better understanding of the factors that influence ophthalmic artery Doppler by examining the possible association between the PSV ratio and maternal cardiovascular function.

METHODS

This was a prospective observational study in women attending for a routine hospital visit at 19 + 1 to 23 + 3 weeks' gestation. This visit included assessment of flow velocity waveforms from the maternal ophthalmic arteries and assessment of maternal cardiovascular function. The following nine cardiovascular indices were examined: E/A ratio; E/e' ratio; myocardial performance index; global longitudinal systolic strain; left ventricular ejection fraction; peripheral vascular resistance; left ventricular cardiac output; left ventricular mass indexed for body surface area; and mean arterial pressure. The ophthalmic artery PSV ratio and the nine cardiovascular indices were converted to either log₁₀ multiples of the median (MoM) values or deviations from the median (deltas) values after adjustment for maternal characteristics and elements of medical history. Regression analysis was then used to examine the significance of the association between PSV ratio delta and MoM or delta values of each cardiovascular index in the total population and in the subgroup that developed PE.

RESULTS

The study population of 2853 pregnancies contained 76 (2.7%) that developed PE. In the total population, there were significant but weak associations between the PSV ratio and most of the cardiovascular indices, with r-values of < 0.1, except for mean arterial pressure with r = 0.178. In the subgroup that developed PE, a moderately strong association between the PSV ratio and left ventricular mass indexed for body surface area was noted (r = 0.308).

CONCLUSIONS

The findings of this study suggest that Doppler assessment of PSV ratio in the ophthalmic artery provides information about peripheral vascular status. The increase in PSV ratio in women who develop PE is associated with increased afterload and an increase in left ventricular thickness. © 2021 International Society of Ultrasound in Obstetrics and Gynecology.

Cardiac output and peripheral vascular resistance during normotensive and hypertensive pregnancy - a systematic review and meta-analysis

BACKGROUND

In-depth insight into haemodynamic changes during normotensive pregnancy may help identify women at risk for gestational hypertensive complications.

OBJECTIVES

To determine the magnitude of changes in cardiac output and its determinants stroke volume and heart rate, and total peripheral vascular resistance during singleton normotensive and hypertensive pregnancies.

SEARCH STRATEGY

PubMed (NCBI) and Embase (Ovid) databases were searched from their inception up to November 2019.

SELECTION CRITERIA

Studies reporting original measurements of haemodynamic parameters during pregnancy together with a non-pregnant reference measurement. Studies including women using antihypertensive medication were excluded.

DATA COLLECTION AND ANALYSIS

Pooled mean differences between pregnant and non-pregnant women, and absolute values of haemodynamic parameters were calculated for predefined gestational intervals using a random-effects model in normotensive and hypertensive pregnancy. Meta-regression analysis was used to analyse group differences in adjustments and absolute values during pregnancy.

MAIN RESULTS

In normotensive pregnancies, cardiac output increased from the first weeks on, reaching its highest level early in the third trimester (mean difference, 1.41 l·min¹ ; 95% CI 1.18-1.63 l·min^-1 ). In parallel, vascular resistance decreased progressively until its nadir in the early third trimester (mean difference, -331 dyn·sec^-1 ·cm^-5 ; 95% CI -384 to -277 dyn·sec^-1 ·cm^-5 ) and then increased slightly at term. In hypertensive pregnancies, the initial cardiac output increase was higher and vascular resistance did not change throughout gestation compared with reference values.

CONCLUSIONS

Hemodynamic changes in women who eventually develop hypertensive complications are substantially different. Serial monitoring and plotting against developed normograms can identify women at risk and may allow timely intervention.

TWEETABLE ABSTRACT

Monitoring haemodynamic changes in pregnancy helps identify women at risk for hypertensive complications.

Preeclampsia Is a Syndrome with a Cascade of Pathophysiologic Events

This review integrates the currently available information on the molecular, cellular, and systemic mechanisms involved in the pathophysiology of preeclampsia. It highlights that the growth, protection, and promotion of the conceptus requires the modulation of an intact maternal immune system, communication between the mother and fetus, and adaptation of the maternal organic functions. A malfunction in any of these factors, on either side, will result in a failure of the cascade of events required for the normal course of pregnancy. Maladaptive processes, initially aiming to protect the conceptus, fail to anticipate the gradually increasing cardiovascular volume load during the course of pregnancy. As a result, multiple organ dysfunctions install progressively and eventually reach a state where mother and/or fetus are at risk of severe morbidity or even mortality, and where the termination of pregnancy becomes the least harmful solution. The helicopter view on pathophysiologic processes associated with preeclampsia, as presented in this paper, illustrates that the etiology of preeclampsia cannot be reduced to one single mechanism, but is to be considered a cascade of consecutive events, fundamentally not unique to pregnancy.

The role of the erythrocyte in the outcome of pregnancy with preeclampsia

The objective of this study was to analyze the relationships of osmotic and mechanical stability of erythrocytes with anthropometric, biochemical, hematologic and hemodynamic variables in pregnant women with preeclampsia (PE). The studied population consisted of 20 normotensive patients and 16 patients with PE. Patients with PE presented worse gestational outcome, greater hematologic impairment, erythrocytes osmotically more stable in vitro, but in conditions of isotonicity with the in vivo medium, in addition to hyperflow in orbital territory, when compared to normotensive patients. The correlation analysis between anthropometric, hematologic and hemodynamic variables in patients with PE indicated that erythrocytes with lower volumes and lower levels of hemoglobin favor the occurrence of a better gestational outcome, because they are more stable and because they are associated with a decrease in the hemodynamic changes present in the disease. This should mean that the tendency to microcytosis, probably due to a mechanism of compensatory mechanical selection, is a desirable characteristic in the disease.

Maternal cardiovascular hemodynamics in normotensive versus preeclamptic pregnancies: a prospective longitudinal study using a noninvasive cardiac system (NICaS™)

BACKGROUND

Preeclampsia is among the most common medical complications of pregnancy. The clinical utility of invasive hemodynamic monitoring in preeclampsia (e.g., Swan-Ganz catheter) is controversial. Thoracic impedance cardiography (TIC) and Doppler echocardiography are noninvasive techniques but they both have important limitations. NICaS™ (NI Medical, PetachTikva, Israel) is a noninvasive cardiac system for determining cardiac output (CO) that utilizes regional impedance cardiography (RIC) by noninvasively measuring the impedance signal in the periphery. It outperformed any other impedance cardiographic technology and was twice as accurate as TIC.

METHODS

We used the NICaS™ system to compare the hemodynamic parameters of women with severe preeclampsia (PET group, n = 17) to a cohort of healthy normotensive pregnant women with a singleton pregnancy at term (control group, n = 62) (1/2015-6/2015). Heart rate (HR), stroke volume (SV), CO, total peripheral resistance (TPR) and mean arterial pressure (MAP) were measured 15-30 min before CS initiation, immediately after administering spinal anesthesia, immediately after delivery of the fetus and placenta, at the abdominal fascia closure and within 24-36 and 48-72 h postpartum.

RESULTS

The COs before and during the CS were significantly higher in the control group compared to the PET group (P < .05), but reached equivalent values within 24-36 h postpartum. CO peaked at delivery of the newborn and the placenta and started to decline afterwards in both groups. The MAP and TPR values were significantly higher in the PET group at all points of assessment except at 48-72 h postpartum when it was still significantly higher for MAP while the TPR only exhibited a higher trend but not statistically significant. The NICaS™ device noninvasively demonstrated low CO and high TPR profiles in the PET group compared to controls.

CONCLUSIONS

The immediate postpartum period is accompanied by the most dramatic hemodynamic changes and fluid shifts, during which the parturient should be closely monitored. The NICaS™ device may help the clinician to customize the most optimal management for individual parturients. Our findings require validation by further studies on larger samples.

External iliac artery Doppler assessment in the prediction of adverse pregnancy outcomes

PURPOSE

The purpose of this study is to investigate the potential role of the mean external iliac artery pulsatility index (EIA-PI) as a predictor of adverse obstetric outcomes such as preeclampsia, gestational hypertension and small for gestational age (SGA).

METHODS

In women attending for first trimester screening at 11 + 0-13 + 6 weeks of gestation, we recorded maternal characteristics and measured EIA mean PI and uterine artery mean PI. We compared EIA mean PI in those that developed preeclampsia (n = 84), gestational hypertension (n = 50) or small for gestational age (n = 444) with those unaffected (n = 3736). Regression analysis was used to first determine which of the factors among the maternal variables were significant predictors of EIA mean PI in the unaffected group and, second, to predict adverse pregnancy outcomes.

RESULTS

In the unaffected group, EIA mean PI increased with maternal age and decreased with mean blood pressure. Additionally, EIA mean PI was lower in cigarette smokers. Compared with the unaffected group, EIA mean PI was significantly lower in women who develop gestational hypertension or SGA below third centile.

CONCLUSION

EIA mean PI in the first trimester is decreased in women who develop gestational hypertension and in those complicated by SGA below third centile. More studies are needed to confirm these findings.

Bioimpedance cardiography in pregnancy: A longitudinal cohort study on hemodynamic pattern and outcome

Background

Pregnancy associated cardiovascular pathologies have a significant impact on outcome for mother and child. Bioimpedance cardiography may provide additional outcome-relevant information early in pregnancy and may also be used as a predictive instrument for pregnancy-associated diseases.

Methods

We performed a prospective longitudinal cohort trial in an outpatient setting and included 242 pregnant women. Cardiac output and concomitant hemodynamic data were recorded from 11^th–13^th week of gestation every 5^th week as well as at two occasions post partum employing bioimpedance cardiography.

Results

Cardiac output increased during pregnancy and peaked early in the third trimester. A higher heart rate and a decreased systemic vascular resistance were accountable for the observed changes. Women who had a pregnancy-associated disease during a previous pregnancy or developed hypertension or preeclampsia had a significantly increased cardiac output early in pregnancy. Furthermore, an effect of cardiac output on birthweight was found in healthy pregnancies and could be confirmed with multiple linear regression analysis.

Conclusions

Cardiovascular adaptation during pregnancy is characterized by distinct pattern described herein. These may be altered in women at risk for preeclampsia or reduced birthweigth. The assessment of cardiac parameters by bioimpedance cardiography could be performed at low costs without additional risks.

Predictive value of ophthalmic artery Doppler velocimetry in relation to development of pre-eclampsia

OBJECTIVE

To test the hypothesis that ophthalmic artery Doppler velocimetry is predictive of the development of pre-eclampsia (PE).

METHODS

This was a prospective cohort study that included pregnant women in the second trimester who had risk factors for PE. Seven ophthalmic artery Doppler parameters, in addition to uterine artery (UtA) Doppler and clinical variables, were investigated for their prognostic value with respect to PE.

RESULTS

A total of 347 women were recruited, of whom 40 developed PE. A comparison of the mean ophthalmic artery Doppler parameter values between women with and those without PE showed statistically significant differences in several parameters: peak systolic velocity, end-diastolic velocity, mean velocity, peak mesodiastolic velocity (PMDV) and peak ratio. After adjusting for confounding variables, only PMDV remained statistically significant (P < 0.001), with an area under the receiver-operating characteristics curve (AUC) of 0.73. The best cut-off for predicting PE was a PMDV of > 22.11 cm/s, with sensitivity of 70%, specificity of 75%, positive likelihood ratio of 2.8, negative likelihood ratio of 0.4, positive predictive value of 28% and negative predictive value of 95%. The AUC increased from 0.72 to 0.78 when the PMDV was incorporated into a prediction model based on clinical variables, demonstrating that this marker increased the discriminatory capability of the model. The performance of ophthalmic artery Doppler was similar to that of UtA Doppler for predicting PE. Additionally, the AUC increased significantly from 0.82 to 0.88 when the PMDV was incorporated into the model containing clinical variables and UtA Doppler indices.

CONCLUSION

A high ophthalmic artery PMDV in the second trimester of pregnancy is an independent predictor of PE that increases the discriminatory ability of clinical markers, as well as of models that include clinical variables and UtA Doppler indices.

Doppler velocimetry of the orbital vessels in pregnancies complicated by preeclampsia

Hypertension is one of the most common clinical complications during pregnancy. Preeclampsia, in particular, still accounts for high maternal and fetal morbidity and mortality. Hemodynamic studies have shown that general arteriolar vasoconstriction, which leads to hypoperfusion of target organs, including the eye area, remains the most significant pathological change in preeclampsia. Color Doppler imaging is the most appropriate and the commonly used method for the study of ocular circulation, especially during pregnancy. It enables the visualization and flow measurement of retrobulbar blood vessels. The aim of this review is to evaluate studies that investigated the role of Doppler velocimetry of the maternal orbital vessels, especially the ophthalmic artery, as a tool for the differential diagnosis of hypertensive disorders of pregnancy, for the assessment of the degree and severity of preeclampsia, and for the prediction of these disturbances. The analysis of these studies indicates that the Doppler variables are accurate in the differential diagnosis of hypertensive disorders and in assessing the severity and progression of the preeclampsia and may also be useful markers in the treatment and management of pregnancy-induced hypertension. We found no study evaluating the role of orbital vessels Doppler variables in predicting preeclampsia or in the prognosis of maternal-fetal adverse events.

Ophthalmic artery Doppler velocimetric values in pregnant women at risk for preeclampsia

OBJECTIVES

The purposes of this study were to describe ophthalmic artery Doppler parameters in pregnant women at risk for preeclampsia in the second trimester, compare them with reference values described in women with healthy pregnancies, and evaluate the association between gestational age and Doppler parameters.

METHODS

We conducted an observational study with prospective data collection in which measurements of 7 ophthalmic artery Doppler parameters were obtained in 274 women at 20 to 28 weeks' gestation with clinical risk factors for preeclampsia. The following measurements were obtained: peak systolic velocity, mesodiastolic velocity, mean velocity, end-diastolic velocity, resistive index, pulsatility index, and peak ratio. The observed Doppler values were compared with reference values by a 1-sample t test. To test for linear associations between gestational age and Doppler parameters, the Pearson correlation coefficient was used.

RESULTS

Significantly higher ophthalmic artery Doppler velocimetric parameters were observed when compared with the reference values. The mean values of these parameters ± SD were as follows: peak systolic velocity, 37.9 ± 10.3 cm/s (reference, 34.2 cm/s; P < .001); end-diastolic velocity, 7.2 ± 3.1 cm/s (reference, 6.8 cm/s; P = .03); resistive index, 0.81 ± 0.07 (reference, 0.70; P < .001); pulsatility index, 2.17 ± 0.53 (reference, 1.80; P < .001); and peak ratio, 0.53 ± 0.12 (reference, 0.40; P < .001). There was no correlation between the Doppler parameters and gestational age.

CONCLUSIONS

Ophthalmic Doppler parameters of women at risk for preeclampsia are significantly higher than reference values for healthy pregnancies, which may indicate an inadequate vascular response to persistent peripheral resistance. Gestational age during the second trimester is not associated with ophthalmic artery Doppler parameters in pregnant women at risk for preeclampsia.

Preeclampsia: pathophysiology and implications for care

Nurses are increasingly encountering pregnant/postpartum women with hypertensive disorders of pregnancy, of which preeclampsia is one of the most common. The Joint Commission published a Sentinel Event Alert in 2010 on prevention of maternal death. This report notes that one of the 5 leading causes of pregnancy-related mortality between 1991 and 1997 was "hypertensive disorder." Preeclampsia presents significant risk to the health of the mother and the fetus. Clearly, nurses must understand the pathophysiology, assessment, management, recurrence risk, and long-term implications of preeclampsia to participate fully in a management plan that promotes safe patient care.

Impedance cardiography facilitates differentiation of severe and superimposed preeclampsia from other hypertensive disorders

OBJECTIVE

To determine if hemodynamic profiling using noninvasive impedance cardiography (ICG) reliably identifies the patient with severe (SPRE) or superimposed (SuPRE) preeclampsia.

METHODS

Late gestation hypertensive pregnant patients underwent immediate ICG evaluation. Findings were compared between patients subsequently achieving or not achieving American College of Obstetricians and Gynecologists criteria for SPRE or SuPRE.

RESULTS

Patients with severe disease were more likely to have depressed cardiac function and higher systolic blood pressure, mean arterial blood pressure, systemic vascular resistance, and thoracic fluid content compared to nonsevere hypertensive disease.

CONCLUSION

ICG hemodynamic profiling of late gestation hypertensive patients can rapidly and reliably identify those with SPRE or SuPRE.

Maternal arterial stiffness in pregnancies affected by preeclampsia

Preeclampsia (PE) is characterized by an aberrant maternal cardiovascular adaptation to pregnancy and increased cardiovascular risk later on in life. The aim of this study was to compare the maternal wave reflections and arterial stiffness in women with established PE and those with normotensive pregnancies, after systematic adjustment for known confounders. This was a cross-sectional study involving 69 normotensive, pregnant women and 54 women with established PE. Maternal wave reflection (augmentation index) and pulse wave velocity of the carotid-radial and carotid-femoral parts of the arterial tree were assessed noninvasively using applanation tonometry. The measurements were adjusted for maternal age, heart rate, mean arterial pressure, and aortic time to wave reflection and expressed as multiples of the median (MoM) of the control group. In the PE group, compared with controls, there was an increase in the median pulse wave velocity of both the carotid to femoral [1.1, interquartile rage (IQR) 1.0–1.3 MoM vs. 0.9, IQR 0.9–1.0 MoM; P < 0.0001] and carotid to radial (1.0, IQR 0.9–1.1 MoM vs. 0.9, IQR 0.9–1.0 MoM; P = 0.01) parts of the arterial tree. In contrast, there were no significant differences between the two groups in the median augmentation index (0.9, IQR 0.7–1.1 MoM vs. 1.0, IQR 0.5–1.8 MoM; P = 0.46). In conclusion, we found that established PE is characterized by increased maternal arterial stiffness but not altered maternal wave reflection.

New developments in pre-eclampsia

It is quite clear that pre-eclampsia is not simply pregnancy-induced hypertension; rather, it is a multisystem disease with pathophysiological changes secondary to reduced organ perfusion. This reduction can be explained by vasospasm secondary to increased sensitivity of the vasculature to usual circulating pressors, and vascular occlusion secondary to activation of the coagulation cascade. Although pre-eclampsia becomes clinically evident late in pregnancy, pathological and pathophysiological changes antedate the clinical syndrome by weeks to months. The syndrome occurs only in pregnancy and is cured by the removal of fetoplacental tissues.

Based on these findings, we have proposed that the inciting pathophysiological change of preeclampsia is reduced trophoblastic perfusion, which produces an agent that perturbs endothelial cells. The altered endothelial functions associated with this insult increase sensitivity to pressors, activate the coagulation cascade and produce the clinical and pathological findings of preeclampsia. Although we feel this hypothesis could explain pre-eclampsia, it is possible that its major value will be to stimulate others to approach this disorder by considering all facets of its pathophysiology rather than merely its hypertensive component.

The appreciation of pre-eclampsia as a disease present from early pregnancy and the potential role of vasodilator prostaglandins have already stimulated therapeutic trials of aspirin in women at very high risk with encouraging results. At present, information is insufficient to determine the risk/benefit ratio of this therapy in lower risk patients, and aspirin therapy should not be used in these women. Another potential modification of therapy, the substitution of phenytoin for magnesium sulphate, does not seem warranted on the basis of either currently available data or on theoretical grounds.

Fruitful directions for research in the near future will be the explanation of the abnormal trophoblastic invasion of pre-eclampsia and the determination of how reduced perfusion translates into a multisystem disease. In addition, aspirin therapy or other potential prophylactic therapies would be greatly aided by the development of new tests with reasonable positive predictive values, in order to identify preeclampsia prior to clinically evident disease.

Maternal cardiac output between 11 and 13 weeks of gestation in the prediction of preeclampsia and small for gestational age

OBJECTIVE

To investigate maternal cardiac output in the first trimester as a predictor of preeclampsia and delivery of small for gestational age (SGA) infants.

METHODS

In women attending for routine care between 11(+0) and 13(+6) weeks of gestation, we recorded maternal variables and measured cardiac output by echocardiography. We compared cardiac output in those that developed preeclampsia (n=83), pregnancy-induced hypertension (PIH) (n=87), or SGA (n=532) with those unaffected by preeclampsia, PIH, or SGA (n=3,591). Regression analysis was used to first determine which of the factors among the maternal variables were significant predictors of cardiac output in the unaffected group and, secondly, to predict each complication by a combination of maternal variables and cardiac output.

RESULTS

In the unaffected group, cardiac output increased with gestation and maternal weight and decreased with maternal age. Cardiac output was higher in parous women, in cigarette smokers, in those taking antihypertensive or beta-mimetic medications, and in those conceiving after in vitro fertilization, and lower in women of Afro-Caribbean origin. Compared with the unaffected group, cardiac output was significantly higher in the preeclampsia and PIH groups and lower in the SGA group. In screening by cardiac output and maternal variables, for a 10% false-positive rate, the detection rates were 43.4% for all preeclampsia, 52% for preeclampsia without SGA, 23.3% for PIH, and 23.9% for SGA.

CONCLUSION

In pregnancies complicated by preeclampsia, PIH, and SGA, alterations in maternal cardiac output predate the clinical onset of the disorders by several months. Maternal cardiac output in the first trimester is increased in women who develop preeclampsia and decreased in women who deliver SGA infants.

LEVEL OF EVIDENCE

II.

Preeclampsia recurrence and prevention

Women with a previous pregnancy complicated by preeclampsia have an increased risk for recurrence in subsequent pregnancies. For severe preeclamptic women in an initial pregnancy, recurrence rates for any type of preeclampsia are very high, approaching 50% in some studies. Significant maternal and fetal complications are more common in recurrent preeclampsia compared with an initial episode. For women who have experienced a pregnancy complicated by preeclampsia, a systematic evaluation for underlying risk factors may identify a specific pathway suitable for a specific intervention. Although some progress has been made in developing potential therapeutic options to prevent preeclampsia recurrence, there is a great need for better data to determine who will benefit most from any specific therapy.

Measure of hemodynamic patterns by thoracic electrical bioimpedance in normal pregnancy and in preeclampsia

OBJECTIVE

To compare the differences in the hemodynamics between normal pregnancy and preeclampsia, using thoracic electrical bioimpedance.

STUDY DESIGN

We compared heart rate, end-diastolic volume, systolic volume, cardiac output, ejection fraction and peripheral vascular resistances in 18 healthy pregnant women with 15 with preeclamptic women at the following intervals: third trimester, 48 h post-partum, 2 and 6 months post-partum. We took the measurements by thoracic electrical bioimpedance. Statistical analysis was performed by means of Wilcoxon rank-sum test and p < 0.05 was considered statistically significant.

RESULTS

The heart rate was lower in the preeclampsia group during the third trimester and the systolic volume was also lower at 48 h post-partum; this implies a lower cardiac output in women with preeclampsia during pregnancy and in the immediate puerperium. The systemic vascular resistances were higher in preeclampsia in the third trimester and at 48 h post-partum. At 2 and 6 months post-partum, the hemodynamic situation had equalized in both groups.

CONCLUSIONS

Preeclampsia is a situation of low cardiac output and high peripheral resistances compared with a normal pregnancy.

Predicting pregnancy-induced hypertension with dynamic hemodynamics

AIM

To study dynamic changes in the hemodynamic parameters in pregnant women during different weeks of gestation and to comprehend changes to the cardiovascular system in normal pregnant women and in patients with pregnancy-induced hypertension (PIH), with the object of finding predictors of pregnancy-induced hypertension.

METHODS

Radialis artery pulse waves of 132 pregnant women were examined from 10 weeks of gestation onward, and the subjects' hemodynamics were examined every 4 weeks.

RESULTS

In the women with PIH hemodynamic changes occurred earlier than the onset of disease and even presented in early pregnancy; there might be another mode, and there were factors disturbing the blood pressure modulating mechanism.

CONCLUSION

The prediction of PIH from the dynamic changes in hemodynamic parameters has significant implications for clinical practice.

Ophthalmic artery color Doppler ultrasonography in mild-to-moderate preeclampsia

OBJECTIVE

To evaluate the hemodynamic changes in mild-moderate preeclampsia using ophthalmic artery Doppler ultrasonography technique.

METHODS

Ophthalmic artery pulsatility and resistivity indices were calculated in 30 mild-moderate preeclamptic women and 30 normotensive gravid women of matched gestational age. Student's t-test was performed to test the significance of difference.

RESULTS

Both indices of peripheral resistance were found to be significantly lower in the ophthalmic arteries of mild-moderately preeclamptic women than those measured in normotensive gravid women at similar stage of pregnancy. In a small number patients whose disease progressed to severe preeclampsia, both indices increased.

CONCLUSION

In patients with mild-moderate preeclampsia, ophthalmic artery color Doppler ultrasonography detects hemodynamic changes that are not present in normotensive gravid women. Reversal of Doppler patterns in a small number of patients with progressive disease supports the hypotheses suggesting the presence of early vasodilation and late vasospasm in the etiology of preeclampsia.

Stress-related preeclampsia: an evolutionary maladaptation in exaggerated stress during pregnancy?

The authors hypothesize that preeclampsia is a stress-related disease and an evolutionary maladaptation of exaggerated stress during human pregnancy. Epidemiologic studies show that relative risk for preeclampsia is increased in many stressful situations. Many risk factors for preeclampsia are stress-related. Low-stress situations, on the contrary, are protective. Stress in pregnancy corroborates all physiopathologic theories for preeclampsia; it does not contradict them. Animals exposed to intense stress show many characteristics of preeclampsia, and some animal models for human preeclampsia have been proposed. The stress-alarm reaction is protective for survival in animals. But the evolutionary maladaptation of this intense stress could lead to preeclampsia in humans.

Maternal hemodynamics and pregnancy outcome in women with prior orthotopic liver transplantation

The aim of this study is to evaluate the hemodynamics and pregnancy outcome of women with prior orthotopic liver transplantation. Hemodynamic measurements by Doppler technique were performed on pregnant subjects with prior orthotopic liver transplantation. Maternal characteristics, renal function, pregnancy complications, delivery indications, delivery mode, and neonatal outcomes were evaluated. Six pregnancies occurred in 5 women after orthotopic liver transplantation at the University of Washington Medical Center (Seattle, WA) between 1991 and 1999. Four of the 6 pregnancies were complicated by chronic hypertension, fetal growth restriction, and preterm delivery. Two pregnancies had worsening hypertension characterized by vasoconstriction in the second trimester despite antihypertensive therapy. These 2 subjects were administered cyclosporine for maintenance immunosuppression and had greater mean arterial pressures preconception and in the first trimester than the other subjects. One of these pregnancies resulted in fetal demise at 25 weeks' gestation. The other subject was delivered at 28 weeks' gestation for nonreassuring fetal status and superimposed preeclampsia. All pregnancies were complicated by renal insufficiency; however, the 2 subjects with poor obstetric outcome had preconception serum creatinine levels greater than 1.5 mg/dL and creatinine clearances less than 40 mL/min. Pregnancies complicated by second-trimester vasoconstriction and moderate renal insufficiency are at risk for preeclamspia, fetal growth restriction, and fetal demise. Good obstetric outcome can occur in women with mild renal insufficiency and well-controlled chronic hypertension. Improved hypertensive control preconception may decrease the risk for preeclampsia and poor obstetric outcome.

Management of complicated preeclampsia

The complicated preeclamptic patient represents a challenge for the clinician faced with her antepartum or postpartum care. The most serious sequelae of preeclampsia account for a significant portion of maternal morbidity and mortality. Severe preeclampsia also results in an appreciable portion of perinatal morbidity and mortality. In this review, developing trends in the treatment of severe preeclampsia are discussed. Expectant treatment of the patient remote from term, anesthesia choices, and delivery route are reviewed. Developing trends in the pharmacological approach to complicated preeclampsia are discussed. New concepts in the treatment of cerebrovascular preeclampsia and hepatic rupture are outlined and reviewed.

Aggressive management of HELLP syndrome and eclampsia

The nursing care of women critically ill during pregnancy is an ever-changing specialty that presents unique clinical problems and issues. The woman and the fetus can be profoundly affected by the hypertensive disorders of pregnancy. The underlying pathology must be identified in relation to its effects on the pregnancy, the effects of the pregnancy on the disease, and the implications for the woman and the fetus. Severe preeclampsia, the HELLP syndrome (hemolysis, elevated liver enzymes, and low platelets), and eclampsia present such challenges and management problems. This article discusses the pathophysiology and management implications of severe preeclampsia, the HELLP syndrome, and eclampsia.

Maternal ophthalmic artery Doppler velocimetry in normotensive pregnancies and pregnancies complicated by hypertensive disorders

OBJECTIVE

Our objective was to compare maternal ophthalmic artery pulsatility index values in normotensive pregnancies and pregnancies complicated by hypertensive disorders.

STUDY DESIGN

The ophthalmic artery in 17 normotensive nonpregnant women, 29 normotensive pregnant women, 9 patients with mild preeclampsia, 6 with severe preeclampsia, 6 with transient hypertension, and 9 with chronic hypertension was studied with color Doppler flow imaging and pulsed Doppler ultrasonography. The mean arterial blood pressure and the ophthalmic artery pulsatility index were calculated in each group.

RESULTS

The pulsatility index (1.17 +/- 0.08) in severe preeclampsia was lowest among the groups p < 0.05), whereas that (2.92 +/- 0.59) in normotensive pregnant women was highest among the groups (p < 0.05). The pulsatility index (1.47 +/- 0.30) in mild preeclampsia was significantly lower than that (1.89 +/- 0.27) in transient hypertension (p < 0.05). There was no significant difference in pulsatility index between mild preeclampsia and chronic hypertension (1.69 +/- 0.49) or between transient hypertension and chronic hypertension. The pulsatility index inversely correlated well with the mean arterial blood pressure (R2 = 0.645, p < 0.0001).

CONCLUSIONS

These results suggest that the lower pulsatility index should be interpreted as orbital vascular vasodilation, indicating orbital hyperperfusion or hyperemia. Changes in pulsatility index in the ophthalmic artery may be indicative of similar changes in other cerebral vessels.

Use of the pulmonary artery catheter in severe preeclampsia: a review

The use of a balloon-tipped, flow-directed pulmonary artery catheter in critically ill and surgical patients has become commonplace in the United States since its introduction into clinical medicine in 1970. The capability of acquiring continuous hemodynamic and, more recently, oxygen transport data, has led to an enhanced understanding of pathophysiologic processes in disease states and to an improved ability to guide therapeutic decision making. The purpose of this paper is to review experience with the pulmonary artery catheter in subsets of women with severe preeclampsia.

Antithrombin III prevents renal dysfunction and hypertension induced by enhanced intravascular coagulation in pregnant rats: pharmacological confirmation of the benefits of treatment with antithrombin III in preeclampsia

We tested the hypothesis that enhanced intravascular coagulation in pregnancy could produce clinical symptoms similar to those of preeclampsia, such as hypertension, proteinuria, and edema. Having confirmed this, we then examined whether the pathological changes caused by intravascular coagulation could be suppressed by administration of antithrombin III (AT III), an endogenous inhibitor active to thrombin and factor X a. Intravascular coagulation was induced in Wistar rats on day 16-20 of pregnancy by 1-h arterial infusion of tissue thromboplastin (TP) through the left ventricle of the heart. One hour after the end of the infusion period, organ blood flows were measured by the radioactive ((57)Co-labeled) microsphere method, and fibrin deposition in organs was measured by radiolabeling with [(125)I] fibrinogen injected before TP infusion. Infusion of TP produced fibrin deposition in the kidney, lung, and liver, but not in the myometrium and placenta, as well as an 80% decrease in renal blood flow (RBF), with oliguria and proteinuria. TP also caused an increase in blood pressure (BP) accompanied by an increase in plasma renin activity (PRA), both of which were suppressed by bilateral nephrectomy before TP infusion. The prophylactic administration of AT III concentrates (60 or 300 U/kg intravenously (i.v.), followed by infusion of 30 or 150 U/kg/2 h, respectively) prevented all pathological changes in a dose-dependent manner. AT III increased placental blood flow regardless of the state of coagulation. These findings suggest that intravascular coagulation plays a significant part in the pathophysiology of preeclampsia and that AT III concentrates may have therapeutic potential in the treatment of this condition.

Possible dietary measures in the prevention of pre-eclampsia and eclampsia

The recurring theme when considering the various dietary manipulations that have been advocated in the prevention of pre-eclampsia is of dietary deficiencies and excesses that appear to be associated with the disease. However, whether these deficiencies and excesses cause, or arise as a consequence of, pre-eclampsia has frequently not been established. Advocates of dietary theories of the aetiology of the disease have tended to base their claims upon uncontrolled clinical trails and inadequate research investigations. With very few exceptions, the better-designed studies have failed to show any effect of dietary supplementation or restriction on the incidence of pre-eclampsia. While certain manipulations, for example calcium and n-3 fatty acid supplementation seem intriguing and merit further study, potentially harmful effects of other manipulations, namely weight restriction (Campbell Brown, 1983), salt restriction (Robinson, 1958) and magnesium supplementation (Lamm et al, 1988), have been demonstrated. The persistent tendency for the medical profession to provide dogmatic and often conflicting advice, and to advocate rigorous intervention, is thus culpable. Until the appropriate research is performed in a less haphazard fashion, with all interventions performed in the context of controlled trials, no dietary intervention can be advocated.

The role of reproductive hormones in vascular disease and hypertension

Review of pertinent research demonstrates a link between sex steroids and vascular disease. Evidence for this association includes: beneficial effect of estrogens on the blood lipids (elevation of high-density lipoproteins and lowering of low-density lipoproteins), adverse effect of high-dose synthetic estrogens on coagulation, vasodilating action of progesterone, and adverse effect of androgens and androgen-derived progestagens on lipoproteins. Natural steroids appear to differ in their impact from synthetic compounds; endogenous hormones from exogenous and parenterally administered preparations. Furthermore, steroids have different effects at different concentrations, doses, and ratios. Their actions also vary according to age, sex, pregnant or nonpregnant state, body weight, smoking, and other risk factors. In this article, the following areas will be considered in relation to the impact of sex steroids on cardiovascular phenomena and hypertension: menstrual cycle and its disturbances; amenorrhea and hyperandrogenism; pregnancy with its hyperdynamic state and a tendency to gestational hypertension; oral-contraception-induced, dose-related thromboembolic phenomena; menopause and estrogen deficiency states with increased incidence of atherogenesis; estrogen replacement therapy with its decrease in cardiovascular morbidity; other hormonal therapies which induce hypoestrogenism with its consequences. The evidence is emerging that hormonal modifications may be useful in the prevention of cardiovascular morbidity.

The role of complement in pregnancy-induced hypertensive disease

Preeclampsia is a pregnancy-induced hypertensive disease with an incidence of about 5% in primigravidas and, being common, it significantly contributes to maternal and neonatal morbidity and mortality. The primary cause remains unknown but might be immunologic, since immunologic aberrations are described in preeclampsia. Activation of the complement system in pregnancy-induced hypertensive disease has been discussed during the last 60 years. It is now strongly indicated that complement activation occurs in preeclampsia. The complement system is very potent and one of the major effector pathways of the process of inflammation. The pathological manifestations, endothelial damage and microvascular injury, and thereby the clinical findings in preeclampsia, may be explained by complement activation, resulting in the direct vascular effects of biological active complement components and complement-mediated activation of leukocytes, with release of potent inflammatory mediators. This new etiological hypothesis might give other options in therapy and prevention of pregnancy-induced hypertensive disease.

Severe preeclampsia: implications for critical-care obstetric nursing

Severe preeclampsia can have a catastrophic effect on maternal-fetal outcome; therefore, perinatal nurses must have a working knowledge of related pathophysiologic processes to perform advanced assessment and interpret data. Technologic adjuncts developed over the past decade, such as the fiberoptic pulmonary artery catheter, allow more precise assessment of maternal hemodynamic status and oxygenation for some patients. With such information, the health-care team can guide therapy to promote optimal outcomes.

Malignant ventricular arrhythmias in eclampsia: a comparison of labetalol with dihydralazine

OBJECTIVE

Our aim was to assess the impact of beta-adrenergic blockade during the peripartum period on the previously observed high incidence of ventricular arrhythmias in eclamptic parturients.

STUDY DESIGN

An open, randomized comparison of intravenous labetalol versus dihydralazine was conducted in 40 eclamptic subjects in the peripartum period. Cardiac rhythm was assessed by blinded analysis of a 24-hour Holter record by means of the Lown classification of arrhythmias.

RESULTS

There was a significantly higher incidence of serious ventricular arrhythmias in patients receiving dihydralazine (81%) than in those receiving labetalol (17%, p < 0.0001). Patients receiving labetalol showed a significant decrease in mean heart rate (p < 0.0001), whereas patients receiving dihydralazine showed a significant increase (p < 0.0001).

CONCLUSION

The introduction of beta-adrenergic blockade into peripartum hypertensive management of eclampsia significantly reduced the incidence of dangerous ventricular arrhythmias. Myocardial oxygen supply/demand ratio may be improved by beta-blockade.

The intensive care management of severe pregnancy induced hypertension

Severe pregnancy induced hypertension (PIH, pre eclampsia) is a disease which is now treated in the intensive care unit rather than with sedation in a dark room. The pathophysiology is now well understood and allows for better and more effective management. This paper looks at the strict haemodynamic monitoring and management required to prevent complications such as eclampsia, DIC, HELLP syndrome, maternal and foetal death. The nurse's role in the management of severe PIH is discussed.